CHAPTER XIV 



BIRDS AND INSECTS : AS PROOFS OF AN ORGANISING 

 AND DIRECTIVE LIFE-PRINCIPLE 



IF we strip a bird of its feathers so that we can see its body- 

 structure as it really is, it appears as the most ungainly and 

 misshapen of living creatures ; yet there is hardly a bird 

 but in its natural garment is pleasing in its form and motions, 

 while a large majority are among the most beautiful in 

 shape and proportions, the most graceful in their activities, 

 and often the most exquisite and fascinating of all the 

 higher animals. The fact is, that the feathers are not merely 

 a surface-clothing for the body and limbs, as is the hairy 

 covering of most mammals, but in the wing and tail-feathers 

 form an essential part of the structure of each species, 

 without which it is not a complete individual, and could 

 hardly maintain its existence for a single day. The whole 

 internal structure has been gradually built up in strict 

 relation to this covering, so that every part of the skeleton, 

 every muscle, and the whole of the vascular system for 

 blood-circulation and aeration have been slowly modified in 

 such close adaptation to the whole of the plumage that a 

 bird without its feathers is almost as helpless as a mammal 

 which f has lost its limbs, tail, and teeth. 



Although birds are so highly organised as to rival 

 mammals in intelligence, while they surpass them in activity 

 and in their high body-temperature, yet they owe this 

 position to an extreme retrogressive specialisation resulting 

 in the complete loss of the teeth, while the digits of the 

 fore limb are reduced to three, the bones of which are more 

 or less united, and, though slightly movable, are almost 

 entirely hidden under the skin. 



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